Styled marks

GeoServer’s CSS module provides a collection of predefined symbols that you can use and combine to create simple marks, strokes, and fill patterns without needing an image editing program. You can access these symbols via the symbol() CSS function. For example, the built-in circle symbol makes it easy to create a simple ‘dot’ marker for a point layer:

* {
  mark: symbol(circle);
}

Symbols work anywhere you can use a url() to reference an image (as in, you can use symbols for stroke and fill patterns as well as markers.)

Symbol names

GeoServer extensions can add extra symbols (such as the chart:// symbol family which allows the use of charts as symbols via a naming scheme similar to the Google Charts API). However, there are a few symbols that are always available:

  • circle

  • square

  • triangle

  • arrow

  • cross

  • star

  • x

  • shape://horizline

  • shape://vertline

  • shape://backslash

  • shape://slash

  • shape://plus

  • shape://times

  • windbarbs://default(size)[unit]

Symbol selectors

Symbols offer some additional styling options beyond those offered for image references. To specify these style properties, just add another rule with a special selector. There are 8 “pseudoclass” selectors that are used to style selectors:

  • :mark specifies that a rule applies to symbols used as point markers

  • :shield specifies that a rule applies to symbols used as label shields (icons displayed behind label text)

  • :stroke specifies that a rule applies to symbols used as stroke patterns

  • :fill specifies that a rule applies to symbols used as fill patterns

  • :symbol specifies that a rule applies to any symbol, regardless of which context it is used in

  • :nth-mark(n) specifies that a rule applies to the symbol used for the nth stacked point marker on a feature.

  • :nth-shield(n) specifies that a rule applies to the symbol used for the background of the nth stacked label on a feature

  • :nth-stroke(n) specifies that a rule applies to the symbol used for the nth stacked stroke pattern on a feature.

  • :nth-fill(n) specifies that a rule applies to the symbol used for the nth stacked fill pattern on a feature.

  • :nth-symbol(n) specifies that a rule applies to the symbol used for the nth stacked symbol on a feature, regardless of which context it is used in.

These pseudoclass selectors can be used in a top level rule, but starting with GeoServer 2.10, they are more commonly used in sub-rules close to the mark property, to get better readability (see example below).

Symbol styling properties

Styling a built-in symbol is similar to styling a polygon feature. However, the styling options are slightly different from those available to a true polygon feature:

  • The mark and label families of properties are unavailable for symbols.

  • Nested symbol styling is not currently supported.

  • Only the first stroke and fill will be used.

  • Additional size (as a length) and rotation (as an angle) properties are available. These are analogous to the (mark|stroke|fill)-size and (mark|stroke|fill)-rotation properties available for true geometry styling.

Note

The various prefixed ‘-size’ and ‘-rotation’ properties on the containing style override those for the symbol if they are present.

Example styled symbol

As an example, consider a situation where you are styling a layer that includes data about hospitals in your town. You can create a simple hospital logo by placing a red cross symbol on top of a white circle background:

[usage='hospital'] {
  mark: symbol('circle'), symbol('cross');
  :nth-mark(1) {
    size: 16px;
    fill: white;
    stroke: red;
  };
  :nth-mark(2) {
    size: 12px;
    fill: red;
  }
}

Also an windbarb example where you get wind speed and direction from your data fields horSpeed and horDir (direction):

* {
  /* select windbard based on speed( here in meters per second, and south hemisphere) */
  mark: symbol('windbarbs://default(${horSpeed})[m/s]?hemisphere=s');

  /* rotate windbarb based on horDir property (in degrees) */
  mark-rotation: [horDir];

  mark-size: 20;
}
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